The polychaete Hermodice carunculata is a voracious predator of several benthic organisms and one of the preferential groups in its diet is that of the cnidarians. This note presents the first record of a fireworm preying on the calcified hydroid Millepora alcicornis. The fireworm engulfs the terminal branches of the fire coral and spends several minutes scraping the surface and removing the soft tissues. Despite this being one of the most common calcified hydroids of the Brazilian northern and northeastern regions (and home to a vast associated community), this kind of association had never been recorded. This discovery points to the need of studying such associations because the damage caused by this polychaete is irreversible and depending on the amount of predators might alter reefs' health or modify the components of the reef community.